Fire retardant composition for urethane polymers

ABSTRACT

A composition comprising a metal salt of a carboxylic acid in conjunction with a beta-haloethyl phosphate has been found useful as a flame retardant for urethane polymers and composites thereof with other polymer materials. The zinc, antimony, stannic and cupric salts of such acids are used in combination with, e.g., tris(beta-chloroethyl) phosphate.

BACKGROUND OF THE INVENTION

In the preparation of polyurethane foam carpeting underlaymentcomposites, a widely used composite comprises a polyurethane foam whichhas been coated on one side with a polyolefin film which acts as a slipsurface to allow the carpet to be easily stretched over the underlay.The polyolefin is normally in contact with the undersurface of thecarpet. If the carpeting catches fire, the polyolefin component of theunderlayment composite acts as a fuel to spread the fire throughout thecarpet and underlayment material. Since flame retardants are, ingeneral, incompatible with polyolefins, it has been found necessary toprovide other means for flame retarding the carpet underlayment materialother than by flame retarding the polyolefin component. Accordingly, themain objective of this invention is to provide a flame retardantcomposition which, when added to the polyurethane component of apolyurethane/polyolefin composite carpet underlay, acts to prevent orretard flammability of the polyolefin component.

SUMMARY

In accordance with the present invention, it has been found that if anorgano-metallic material and a beta-haloethyl phosphate, whichdecomposes to provide a volatile halide, are incorporated in thepolyurethane component of a polyurethane/polyolefin underlaymentcomposite, the halogen volatilizing from the beta-haloethyl phosphateacts to reduce the flammability of the polyolefin component.Additionally, it has been found that beta-haloethyl phosphate esters actto enhance the action of the organo-metallic materials and therebyprovide increased flame retardance for the underlay. It has further beenfound that nonhalogenated phosphate esters may also be incorporated inthe flame retardant composition of the present invention so that theflame retardant composition will thereby be more easily blended into thepolyurethane material.

It has thus been found that zinc, antimonic, stannic and cupric salts oforganic acids in combination with beta-haloethyl phosphates act as anenhanced flame retardant composition.

The organic acid salts which form one component of the flame retardantcomposition of the present invention comprise the zinc, stannic, cupricand antimonic salts of organic carboxylic acids having from 1 to about18 carbon atoms. Exemplary acids which react with the described metalsto form salts include formic, acetic propionic, butyric, valeric,caproic, heptoic, caprylic, pelargonic, capric, lauric, isoacetic,palmitic, margaric, stearic; acrylic, crotonic, oleic; oxalic, malonic,succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic,glutaconic, maleic, fumaric, citraconic; benzoic, phenylacetic, toluic,dihydrocinnamic; phthalic, diphenic; cinnamic and benzalpropionic.

The metal salts are prepared by methods well known in the art, such asby addition of the metal carbonate to an acid solution or by titrationof the appropriate organic acid solution with the appropriate metalhydroxide.

The second component of the flame retardant composition of the inventionis a beta-haloethyl phosphate, i.e., simple and complex phosphatescontaining a beta-haloethyl group, e.g. a mono-, di- or tri-phosphatewherein at least one ester group contains a beta-haloethyl moiety, i.e.the radical --CH₂ CH₂ X, wherein X represents halogen such as chlorineor bromine. The beta-haloethyl phosphates may be simple phosphates ormay be complex, i.e., bisphosphates, polymers and the like. Simplebeta-haloethyl phosphates include diphenyl beta-chloroethyl phosphate,diisodecyl beta-chloroethyl phosphate, di-2-ethylhexyl beta-chloroethylphosphate, dicresyl beta-chloroethyl phosphate, diisooctylbeta-chloroethyl phosphate, di-tributoxyethyl betachloroethyl phosphate,dibutyl beta-chloroethyl phosphate, diisooctyl beta-chloroethylphosphate, isooctyl bis(beta-chloroethyl) phosphate,tris(beta-chloroethyl) phosphate, dicresyl beta-bromoethyl phosphate,diphenyl beta-bromoethyl phosphate, di-2-ethylhexyl beta-bromoethylphosphate, tris(beta-bromoethyl) phosphate, beta-haloethyl phosphatesprepared from 7, 9 or 11 carbon atom alcohols or mixtures thereof, e.g.deheptyl beta-chloroethyl phosphate, dinonyl beta-chloroethyl phosphate,diundecyl betachloroethyl phosphate, di-C₇,9,11 beta-chloroethylphosphate, heptyl bis(beta-bromoethyl) phosphate, nonylbis(beta-bromoethyl) phosphate, undecyl bis(beta-bromoethyl) phosphate,C₇,9,11 bis (beta-bromoethyl) phosphate and similar materials.

Complex phosphates utilized herein include compounds set out in formulaII of U.S. Pat. No. 3,192,242, e.g., 2,2-bis(chloromethyl) trimethylenebis-[di(2-chloroethyl) phosphate] and the bis and polyphosphates setforth at column 1, lines 32 through 40 of U.S. Pat. No. 3,014,956, andparticularly the phosphate set forth at column 28, lines 62 through 65thereof.

Additionally, the composition of the invention may optionally containnon-halogenated phosphate esters such as isodecyl diphenyl phosphate,2-ethylhexyl diphenyl phosphate, 2-ethylhexyl dicresyl phosphate,isooctyl diphenyl phosphate, tributoxyethyl phosphate, tributylphosphate, tricresyl phosphate, triphenyl phosphate, t-butyl diphenylphosphate, m-ethylphenyl diphenyl phosphate, isopropylphenyl diphenylphosphate, diisopropyl phenyl phosphate, triisopropyl phosphate.

The amount of the flame retardant composition which is added to theurethane polymer is from about 2 to about 25 phr (parts per hundredresin) total flame retardant, preferably from about 5 to about 15 phr.Particularly preferred is a flame retardant concentration of from about5.5 to about 11 phr.

The metal salt is normally added in an amount of from about 0.1 to about1.5 phr, preferably from about 0.1 to about 1.0 phr.

The beta-haloethyl phosphate is normally added in an amount of fromabout 4 to about 20 phr, preferably from about 5 to about 10 phr.

In the flame retardant composition itself, the ratio of acid salt tobeta-haloethyl phosphate is from about 1:10 to about 1:55, preferablyfrom about 1:10 to about 1:20.

Of course, the non-halogenated phosphate ester may be added in an amountof from about 10-300 percent, based on the amount of salt. Normally thenon-halogenated phosphate is used in an amount of about 100 percent ofthe amount of salt.

The flame retardant composition may be added to the urethane polymer byseparate metering into the mixing head or by dissolving the flameretardant in a polyol, silicone fluid or another flame retardant orother component.

The urethane polymers which are contemplated in accordance with thepresent invention are polyether polyols from ethylene oxide, propyleneoxide, tetrahydrofuran and copolymers reacted with toluene diisocyanate,polymeric isocyanates, 4,4'-diphenylmethane diisocyanate or aliphaticdiisocyanates, water, blowing agents, surfactants and curatives as iswell known in the art. Polyester polyols prepared from di- or tri-basicacids may be used in lieu of polyether polyols.

Particularly preferred are urethane polymers which have been foamed.

The following examples will illustrate specific embodiments of theinvention contemplated by applicants and are not to be considered alimitation thereof.

EXAMPLE 1

This example illustrates results obtained by testing the flammabilitycharacteristics of a polyethylene/foamed polyurethane laminate.

The test laminate is prepared by thermally laminating a 1-4 mil lowdensity polyethylene film to a polyether/polyurethane foam having adensity of 1.8 to 2.6 pounds per cubic foot and a thickness of one-halfinch to three-fourths inch. The completed laminate is useful as a carpetunderlay.

The polyurethane described above is prepared as follows:

    Ingredients        Weight (Grams)                                             ______________________________________                                        POLYOL GP-3030*    100.00                                                     Water              4.00                                                       Triethylene diamine                                                                              .65                                                        Silicone           1.00                                                       Tolylene diisocyanate                                                                            54.00                                                      Stannous octoate catalyst                                                                        .16                                                        ______________________________________                                         *Polyether Polyol manufactured by Wyandotte Chemical Co.                 

To replicate samples of the above formulation there are added variousflame retardants and metal salts. The flame retarded polyurethane isthen foamed and thermally laminated to the above-described polyethylenefilm to form a composite which is then tested for flame retardantproperties.

The test is conducted in accordance with DOC FF 2-70 which provides amethod to determine the surface flammability of small carpets and rugswhen exposed to a standard source of ignition under carefully prescribeddraft-protected conditions. The method involves the exposure of each of8 conditioned, replicate specimens of a small carpet or rug to astandard igniting source in a draft-protected environment andmeasurement of the proximity of the charred portion of the sample to theedge of the hole in a prescribed flattening frame. A specimen passes thetest if the charred portion does not extend to within 2.54 centimetersof the edge of the hole in the flattening frame at any point. In orderto conform to the standard, at least 7 of the 8 specimens must meet thetest criteria.

In general, the test involves placing an approximately 22.9 centimetersquare specimen of a small carpet or rug in a test chamber. On thespecimen there is placed a methenamine tablet on a point correspondingto the center of the hole (diameter = 22.8 cm) in the flattening frame.The tablet is ignited by touching a lighted match or equivalent ignitingsource carefully to its top. The test is continued until the lastvestige of flame or glow disappears or until the flaming or smolderinghas approached within 2.54 centimeters of the edge of the hole (having adiameter of 22.8 cm) in the flattening frame at any point. When allcombustion has ceased, the test chamber is ventilated and the shortestdistance between the edge of the hole in the flattening frame and thecharred area is measured and recorded. If the charred area does notextend to within 2.54 centimeters of the edge of the hole in theflattening frame at any point, the carpet or rug meets the acceptancecriteria. This test is more specifically described in the FederalRegister, Volume 35, No. 74, page 6,213.

Accordingly, the laminate described above is tested. The variousreplicate groups of laminates are flame retarded with the materialsshown in the Table below. The test results are shown with relation tothe diameter of the burned hole.

                                      TABLE                                       __________________________________________________________________________    Flame Retardant                                                                          Parts per hundred of resin                                         __________________________________________________________________________    PHOSGARD 2XC20.sup.1                                                                     6  6  6                                                            FIREMASTER T-23-P.sup.2                                                                  -- -- -- 6  6  6                                                   FYROL FR-2.sup.3                                                                         -- -- -- -- -- -- 6 6  6                                           Zinc Octoate                                                                             -- .6 -- -- .6 -- --                                                                              .6 --                                          Zinc Oleate                                                                              -- -- .6 -- -- .6 --                                                                              -- .6                                          Diameter of Burn                                                                         8.9                                                                              7.7                                                                              7.1                                                                              8.9                                                                              6.4                                                                              9.7                                                                              B B  B                                            (centimeters)                                                                           B           B                                                      __________________________________________________________________________     .sup.1 Trademark of Monsanto Company. 2,2-Bis-(chloromethyl) trimethylene     bis-[di(2-chloroethyl) phosphate].                                            .sup.2 Trademark of Michigan Chemical Co. Tris(2,3-dibromopropyl)             phosphate.                                                                    .sup.3 Trademark of Stauffer Chemical Co. Tris(dichloropropyl) phosphate.

Of the three fire retardant materials used, only PHOSGARD 2XC20 containsa beta-haloethyl group, i.e. betachloroethyl.

The test data are interpreted as follows:

1. A whole number indicates the distance across the hole burned in thelaminate.

2. A fraction indicates the distance across the hole in the polyurethane(numerator) and indicates that the polyethylene continued to burn afterthe polyurethane extinguished. Thus, the whole number 2 would indicatethat the laminate, after extinguishing, had a burn hole 2 centimeters indiameter. A fraction such as 2/B would indicate that the polyethylenecontinued to burn after the polyurethane extinguished leaving a burnhole 2 centimeters in diameter.

3. The designation B, by itself, indicates that the laminate burns.

The above data show that flame retardance of PHOSGARD 2XC20 is improvedby the addition of metal salt; that tris(2,3-dibromopropyl) phosphateshows no improvement, and actually performs worse, with the addition ofmetal salt; that tris(2,3-dichloropropyl) phosphate fails in allinstances.

Combinations of beta-haloethyl phosphates and metal salts of acids suchas zinc formate, zinc stearate, stannic butyrate, cupric caproate,antimonic laurate, zinc palmitate, antimonic stearate, cupric oleate,zinc sebacate, stannic benzoate, cupric phthalate with diisodecylbeta-chloroethyl phosphate, di-2 -ethylhexyl beta-bromoethyl phosphate,dicresyl beta-chloroethyl phosphate provide like results.

EXAMPLE 2

Laminates prepared as in Example 1 are retested but a replicate group ofsamples is formulated which contain an optional non-halogenatedphosphate as part of the flame retardant formulation. Thenon-halogenated phosphate, isodecyl diphenyl phosphate assists thework-up of the zinc salt into the polyurethane foam.

Results are shown in the Table below:

                    Sample No.                                                    Flame Retardant   1     2      3   4    5   6                                 ______________________________________                                        FYROL FR-2        --    --     10  10   --  --                                PHOSGARD 2XC20    10    10     --  --   10  10                                Zinc Oleate       --    .5     --  .5   --  --                                Zinc Octoate      --    --     --  --   --  .5                                Isodecyl Diphenyl Phosphate                                                                     --    .5     --  .5   .5  .5                                Diameter (Centimeters)                                                                          6.1   5.1    7.6 8.9  5.8 5.1                               ______________________________________                                    

The data show:

1. Tris(dichloropropyl) phosphate performs worse with the addition ofmetal salt even at this increased concentration.

2. Performance of the phosphate containing a betachloroethyl group isimproved by addition of metal salt and/or a non-halogenated phosphateester.

While the invention has been described by referring to certain specificembodiments, it is not so limited since many modifications andvariations are possible in the light of the above teachings. Theinvention may therefore be practiced otherwise than as specificallydescribed without departing from the spirit and scope thereof.

What is claimed is:
 1. A flame retardant composition comprising a saltof a carboxylic acid and a metal selected from zinc, antimony, tin andcopper and a beta-haloethyl phosphate.
 2. Composition of claim 1 whereinsaid metal is zinc.
 3. Composition of claim 1 wherein said metal isantimony.
 4. Composition of claim 1 wherein said metal is tin. 5.Composition of claim 1 wherein said metal is copper.
 6. Composition ofclaim 1 wherein said acid contains from 1 to about 18 carbon atoms. 7.Composition of claim 1 wherein said phosphate is a beta-bromoethylphosphate.
 8. Composition of claim 1 wherein said phosphate is abeta-chloroethyl phosphate.
 9. Composition of claim 1 which contains anon-halogenated phosphate.
 10. Composition of claim 9 wherein saidphosphate is isodecyl diphenyl phosphate.
 11. Composition of claim 1wherein said acid salt is selected from zinc octoate, zinc oleate andzinc stearate and said phosphate is 2,2-bis(chloromethyl) trimethylenebis[di(2-chloroethyl) phosphate].
 12. Composition of claim 1 wherein theratio of said salt to said phosphate is from about 1:10 to about 1:55.